For most of the history of television, the barrier to syndication—and to profitability—has been 100 episodes. The shows that have made it to that mark are an unusual group. Many were big hits. Some found small cult audiences. Still others just hung on as best they could and never posted numbers quite low enough to be canceled. In 100 Episodes, we examine the shows that made it to that number, considering both how they advanced and reflected the medium and what contributed to their popularity.

“A private eye—in the classical tradition,” was Joe Mannix’s modest self-description, delivered with a wry smile. It was a throwaway line from an early episode, repurposed ad nauseam in clever TV Land ads that touted the series’ twice-a-day reruns during the late 1990s. But it captured the ethos of Mannix, a no-frills detective drama that was the template for a glut of crime series that choked the airwaves during the early ’70s (and Mannix was more a show of the ’70s than the ’60s, even though it debuted in 1967). Cannon was the fat private dick, Barnaby Jones was the old one, Longstreet was the blind (yes, blind) one. Mannix was the original model. Like the early seasons of ER or C.S.I., Mannix was put together with skill and care, but its mainstream success made it easy to take for granted.

Mannix was easy to take, period. The low-key personality of Mike Connors, the former basketball player and B-movie actor who played the title character, set the tone. Likable but flinty, Connors was a tough guy who didn’t have to show off. An idealist and a nice guy, Mannix was perfectly willing to take on a lost little girl as a client and negotiate his fee in lunch money (never actually collected, of course). Connors had a rare sincerity that kept scenes like that from getting corny. (When cynical private eye shows like Harry O and The Rockford Files made a point of their protagonists’ pragmatic eye for a buck, it was mainly Mannix they were rebuking.) Working out of a comfy Spanish-styled home office, dressed in plaid sport coats made out of fabric as thick as carpet, driving a snazzy muscle car painted a hideous shade of army-Jeep green, Joe Mannix was functional but square. It was all of a piece. Mannix was the audience’s uncle or its brother-in-law—that quiet, comforting fellow who never let on that he’d mowed down a whole squadron of advancing enemies during the war. (Joe’s actual backstory included service in Korea; another often-mocked TV trope, the one where the deranged vet returns to kill off all the members of his old platoon, comes more from Mannix than any other single show.) Mannix’s secretary, Peggy Fair, was cannily drawn to underscore his avuncular solidity. Played by Gail Fisher, one of the more prominent African-American actors on television at the time, Peggy was the widow of a cop, so naturally he’d never make a pass. She was also a single mother, which meant that the producers could show Mannix in surrogate dad mode whenever little Toby (Mark Stewart) turned up.

Mannix was a fabulously violent program. Joe Mannix got brained on the back of the head or shot in the shoulder in just about every episode. If the primary bad guys were recognizably human characters, the anonymous bruisers who did their bidding, usually clad incongruously in suits and always in pairs, were a class of criminal that existed only on television: Goons ’R’ Us. Not content to use their fists, this ever-replenishable army of nameless hoods attacked Mannix with motorcycles, dune buggies, race cars, helicopters. And yet Mannix went down so easily that, no matter how often critics singled out its brutality, it escaped unscathed; other shows, like The Outsider (a rival P.I. series starring growly Darren McGavin, who had been considered early on to play a more roughhewn Mannix), were retooled or canceled in the wake of the 1968 assassinations, but Mannix grew ever more baroquely violent. Mannix had one of the all-time great theme songs, by Lalo Schifrin, who had made his name a season before with the iconic theme for Mission: Impossible (a sort of sibling to Mannix, also produced on the Paramount lot by a unit under producer Bruce Geller). But while Schifrin’s Mission: Impossible theme was brassy and urgent, his Mannix music was a toe-tapping suite of coffeehouse jazz. With Schifrin’s main title tune rattling around in their heads for the duration of the hour, viewers couldn’t get too worried about what was going to happen to their hero. Everything about Mannix fostered a sort of harmoniously agreeable mood. It was comfort-food television, in the best sense.

But Mannix began as something much less high-concept: an intellectual take on the private-eye genre from William Link and Richard Levinson, the creators of Columbo. During its first season—so different from what followed that it was usually excluded from syndication—Joe Mannix worked for a large, efficiency-oriented private-detective firm, whose operatives were valued less than the firm’s gigantic crime-solving data center. Mannix, an ex-cop, took an intuitive, old-school approach that put him at odds with the head of Intertect, Lew Wickersham (Joseph Campanella). Man versus machine: Joe Mannix was John Henry and the steam hammer was a computer. Intertect, as Link and Levinson originally titled the show, was meant as an allegory, in which the familiar cloak of the mystery genre would conceal a critique of soulless, modern corporate life.

Wickersham’s name was a pun on that of Hollywood mogul Lew Wasserman and also Lankershim Boulevard, where sat the main entrance to Universal Studios. In 1959, Universal had been acquired by MCA, a talent agency with a reputation for ruthlessness. Its agents, many of whom became Universal executives, wore uniform black suits and ties, and MCA president Wasserman was known for his scary bursts of temper and his always-empty desk (paper was for underlings). By the late ’60s, Universal was the biggest television factory in the industry; it conducted business out of an ominous glass-walled slab nicknamed “The Black Tower,” and was the first studio to keep track of its employees using computer punch cards. Link and Levinson, who had written for Alfred Hitchcock Presents there, incorporated all of these details into the original format of Mannix, making Intertect a rich inside joke.

Unfortunately, Link and Levinson were out even before the cameras turned on the pilot. The pair sold the idea to Desilu (Lucille Ball’s production company), which placed it in the hands of Bruce Geller (the creator and executive producer of Mission: Impossible), who hired Wilton Schiller (of Ben Casey and the lackluster final season of The Fugitive) to produce. By the time Mannix passed through all those hands, no one involved knew how to write it. Mannix and Wickersham bickered with each other every week like the Kramdens, but the hot air had little to do with their cases, and changed nothing. Since both characters had to keep showing up for work, Mannix was locked into a talky stasis. Link and Levinson’s clever premise would have worked better 30 years later, in a semi-serialized show like The X-Files, where one-off mysteries could alternate with a deeper mythology about the sinister and soul-crushing nature of Intertect.

Mannix was a bubble show in 1968, and rather than scrap it or try to fix the stillborn Mannix/Wickersham conflict, Geller and CBS opted to revamp the format as a traditional—some might say generic—detective drama. A sarcastic Levinson imagined the network meeting that okayed the format change: “‘What have you got?’ ‘A private eye who solves cases.’ ‘Brilliant!’” Campanella was let go and Schiller was replaced by Ivan Goff and Ben Roberts, veteran screenwriters (White Heat; Midnight Lace) with good taste in directors and guest stars and a knack for intricate stories. Connors and the new producers agreed to discard Joe Mannix’s hard-edged, wisecracking Intertect-era persona and try for a rarer strain of romanticism. Now Mannix would love the ladies and lose them, would confront his estranged father (a central California vintner, stubborn like Joe Mannix and of Armenian heritage like Connors, played by Victor Jory in a pair of episodes), would play the white knight when Peggy or his old pals or girlfriends got into trouble. Instead of Wickersham and his computer, Mannix would spar with a steady rotation of recurring cops (including Robert Reed as Lt. Adam Tobias, a guest star whose banter with Connors was so free-wheeling and enjoyable that Mannix brought him back whenever he could get free of his regular gig as dad to The Brady Bunch). Goff and Roberts made sure to commission a couple of episodes each season in which Mannix was shot or blinded or—as in “The Mouse That Died,” a riff on the 1950 film D.O.A.—dosed with a slow-acting poison. It was shameless Emmy bait, and it worked surprisingly well. Mannix netted a slew of nominations (including four for Connors, two for best drama, and a win for Fisher, a showing that was only possible in an era when action shows had crowded out most serious dramas off the air), and an even bigger haul at the Golden Globes.

More creatively satisfying than the stunt episodes, though, were the fatalistic, character-driven mysteries that were the show’s regular fare. Under Goff and Roberts’ tenure, Mannix was written by a corps of television’s best crime specialists, including Stephen Kandel, Ed Adamson, Frank Telford,Robert W. Lenski (a former police beat reporter who had written only a few variety specials prior to Mannix), and themselves (under the pseudonym “Blake Ritchie”). In their hands, Mannix was not a sleuth so much as an island of competence amid a succession of lives in tragic disarray. Mannix was too traditional a hero to lose any cases, but the catch was that solving the case didn’t always solve the client’s problems. In “Odds Against Donald Jordan,” for instance, Mannix tries to rescue Jordan (James Olson) from some hoods seeking, at gunpoint, to collect an unpaid gambling debt. It turns out that the mobsters don’t care enough to kill, and the whole thing is Jordan’s ruse to steal another gambling stake from his friends and family. In the end all Mannix can do is stage an intervention. Mannix was too smooth, too ’70s to qualify as neo-noir, but more than anything else on television it did echo the flavor of its era’s most unsentimental crime novelists, authors like Ross Macdonald, John D. MacDonald, Richard Stark.

But the most exciting element of Mannix is its imagery, which was flamboyant in the tamer episodes and unhinged in the rest. Take zooms, rack focuses, lens flares, extreme wide and long lenses, extreme low, overhead, and Dutch angles, handheld and gyroscope-mounted cameras, and deep multiplanar compositions, then add a lysergic dose of pop-art production design and 52-card pick-up editing, and you have the house style of Mannix. Like many of the more visually inventive shows of the late ’60s and early ’70s, Mannix reflected two very different, but in some ways convergent, sources: the European New Wave cinema and television commercials, which had incubated many catchy, cutting-edge visual gimmicks to snare viewers’ attention in their allotted seconds.

Stuart Hagmann, who directed four of the best Mannix episodes in 1968 and 1969, came out of commercials; still in his 20s, he had gained attention for some Eastman Kodak ads that aired during the 1967 Oscars. A long sequence in “Odds Against Donald Jordan” has Mannix offering a sympathetic shoulder to Jordan’s wife (Susan Oliver) at the same time he’s gently interrogating her. Hagmann opens with a shot of the pair in Mannix’s convertible, taken through the windshield, as the dense foliage overhead is reflected in the glass. The shadows of the leaves are so thick that Oliver and Connors are barely visible underneath them. An abrupt cut finds the two on the beach and (via an even bolder jump cut) on a pier, eating hot dogs. Hagmann cuts away to seagulls in flight or congregating on the sand, and to the orange ball of the sun on the horizon; eventually the birds and the sunset are superimposed over one another. Much of the dialogue is heard over these abstract images. In the last part of the scene, Hagmann starts with an extreme long shot of Oliver and Connors on the pier and pulls back even further, leaving them barely visible in silhouette as Mannix cuts to commercial. Imaginative as the visuals are, they don’t overpower the wistful performances by Oliver and Connors, who hint at an unconsummated attraction. The same scene could have been staged just as easily in a living-room set; and had this been an episode of Ironside (whose star, Raymond Burr, didn’t like to leave the studio) it probably would have been.

Paul Krasny, who had been the supervising film editor for Mission: Impossible and Mannix while still in his early 30s, debuted as a director on the former series. Predictably adept at rapid, complex editing, and expert at staging action and chase sequences, Krasny directed more Mannixes than anyone else (over two dozen) and set the style for the later seasons. One of the best Krasny showcases is “Death Is The Fifth Gear,” in which slow motion, solarization, optical effects, and a series of dense montages are used convey Mannix’s disoriented state after he flames out in an auto race. Sutton Roley, another prolific Mannix director, favored wide-angle lenses and had a fetish for framing actors within some looming foreground object. The quintessential Roley shot was a long take in which the camera makes two or three forceful moves, each time emphasizing a shift in the scene by reframing the actors in some striking arrangement within the set. In the terrific “The Solid Gold Web,” Roley stages a romantic scene—a rekindling of the feelings between Mannix and a troubled old flame (Sally Kellerman) during a slow dance—in a two-minute take photographed through a bird cage, in which parakeets flit back and forth in the foreground, out of focus, repeatedly obscuring and then revealing the lovers.

The caged-bird metaphor is potent, but does the dialogue actually register? Roley has a cult reputation among TV aficionados as a gonzo stylist, whose compositions were always dazzling but could at times overpower the content of a scene. On Mannix, though, Roley fit in perfectly. He was part of a consistent roster of aggressively camera-oriented directors that also included Leonard J. Horn (first among equals as the director of Mannix’s pilot, and of the first feature film Geller produced, Corky), Barry Crane (formerly the line producer for Mission: Impossible, a series known as “the director killer” because its rapid pacing required an unusually high number of camera set-ups), and Reza Badiyi (designer of the opening titles for Hawaii Five-O and Mary Tyler Moore). Geller, who had also given Mission: Impossible a bold look, understood that action shows needed a kinetic texture. Joe Mannix lived in a violent world, and Mannix was built out of violent filmmaking.

Mannix ran for eight seasons and was still in the Nielsen Top 20 when it was canceled, apparently in an obscure falling-out between Paramount (which had bought Desilu, and its shows, in 1967) and CBS over late-night syndication of the series, which the network feared would cut into new episodes’ ratings. Goff and Roberts went on to create Charlie’s Angels, proving that no talent, no matter how skilled, could produce quality work in the employ of Aaron Spelling. Plans for a TV-movie revival of Mannix, almost inevitable for a hit show of the ’70s, collapsed with Bruce Geller’s death in a plane crash in 1978, although Connors did reprise the character in a nostalgic 1997 Diagnosis: Murder that reassembled three surviving guest stars for a sequel to the episode “Little Girl Lost.” It’s a sign of how unassuming the character was that there hasn’t been a new Mannix, even as schlocky relics like Ironside and The Bionic Woman have been revived in the current millennium. If it has to happen, they might as well remake it now—while Connors is still available to play the new Joe Mannix’s dad.

On June 18: 100 Episodes makes the big move to Wednesdays, with Todd VanDerWerff’s thoughts on The Jerry Springer Show.